As per the Regulating Act of 1773, the Governor of Bengal became the GOVERNOR GENERAL OF BENGAL as now the power started to concentrate in the hands of the Governor in Calcutta. Hence, Warren Hasting became Governor General of Bengal.
But later after, CHARTER ACT 1833, William Bentick became the Governor General of India.
Now what has changed? The answer is the area under British Control. By, Bentick's time it has become sufficiently large as compared to Warrent Hasting. So the answer to you question is WILLIAM BENTICK !!